1. Field of the Invention
The present invention relates to an assembly structure of a writing instrument, and more particularly, to an assembly structure of a writing instrument including writing instruments such as a ballpoint pen, highlighter, roller pen, board marker pen, oil-based marker pen, magic pen, plastic pen, or marking pen.
2. Description of the Related Art
Typically, a writing instrument is used to record information on a surface using a recording medium, and has various forms and methods such as a ballpoint pen, highlighter, roller pen, board marker pen, oil-based marker pen, magic pen, plastic pen, or marking pen. Most of these types of writing instruments are generally retractable type writing instruments which are provided with a cylindrical body, a nib housed in the body, and a pushing member provided in the body so as to press the nib.
As a prior art of an example of such a writing instrument, there is a “retractable type writing instrument having a drying prevention unit” as disclosed in Korean Patent Registration No. 10-0817202 (published on Mar. 23, 2008), which has been filed and registered by the present applicant.
The “retractable type writing instrument having a drying prevention unit” is a retractable type writing instrument provided with a drying prevention unit for preventing a nib 41 from becoming dry out, and includes: as illustrated in FIG. 1, a knock part 30 coupled to a shaft 10 having a front opening 11 formed in one end thereof so as to make the nib 41 protrude therefrom or be retracted therein; a cartridge 40 inserted into the shaft 10 in a state in which the knock part 30 and the nib 41 are coupled to both ends thereof; a spring 50 installed within the shaft 10 so as to allow the cartridge 40 to return to its original position by an elastic restoring force thereof; an O-ring 60 supported by the spring 50 and fixedly fitted in the shaft 10; a holder 70 fixedly fitted in the shaft so that one end thereof is covered by the O-ring 60; a link 80 which is slidably fitted in the holder 70 and has a plurality of elastic lugs 85 formed at one end thereof, which move up and down along the holder 70 within a predetermined movement range, wherein the elastic lug 85 is locked to a step 48 of the cartridge 40 by a locking part formed at an end thereof; and a ball type door 90 connected to the link 80 by inserting a parallel pin 82 formed at the other end thereof into a pin slit 92 formed therein. When the cartridge 40 and the link 80 are moved forward from the fixed O-ring 60 and the holder 70 by pushing the knock part 30, the parallel pin 82 moves the pin slits 92 of the ball type door 90, and thereby the ball type door 90 is rotated about a pivot shaft 93 which is supported by spherical parts 70a to open the inside of the shaft. In this state, the nib 11 protrudes from the front opening of the shaft.
Herein, as illustrated in FIG. 1, for assembling the writing instrument, the cartridge 40, the link 80, the ball-type door 90, and the like are sequentially inserted into a rear opening 14 of the shaft 10 to perform the assembly.
Therefore, it is difficult to assemble each part into the long cylinder shaft 10, and there are problems that, if a sealing defect occurs in the writing instrument, it may be determined to be a defective product even when it operates well, and if other defect factors are contained in the writing instrument, there is no way to determine it to be a defective product.
Further, parts for sealing are located at the front end of the shaft 10, and since quality control of the parts for sealing and the protruding or retracting operation is difficult, these parts should be produced for each model, and thereby each part requires specific production facilities.